The present invention relates generally to air cleaners. More particularly, the present invention relates to inertial separation devices for removing particles or droplets from a fluid stream.
Air pre-cleaners are commonly used to remove contaminants (e.g., dust or other particulate matter) from the intake streams of internal combustion engines. U.S. Pat. No. 1,641,746 discloses an air cleaner that uses an inertial separation process to remove particles from an air stream. The cleaner disclosed in the ""746 patent includes a housing 7 having an annular intake passage 14 and an outlet tube 10. A plurality of oblique vanes 12 are positioned within the intake passage 14. The vanes 12 cause the intake air passing through the intake passage 14 to swirl in a spiral motion as the intake air enters the housing 7. The swirling action of the intake air causes particulate matter within the air to be centrifugally thrown against the side wall of the housing 7 and collected in a dust chamber 15. Clean air exits the housing 7 through the outlet tube 10.
U.S. Pat. No. 3,973,937 discloses another type of inertial air cleaner for removing particulate matter from the intake air stream of an internal combustion engine. The ""937 patent discloses an air pre-cleaner having a housing 113 including an annular air inlet passageway 122 and a tubular outlet passage 119. A plurality of swirling vanes 126 are positioned within the inlet passageway 122, and spinner assembly 133 is located within the housing 113. In use, air flows through the air inlet passage 122 and is caused to swirl within the housing 113. Particulate material within the swirling air stream is centrifugally thrown against a side wall of the housing 113 and discharged to atmosphere through a discharge opening formed in the side wall of the housing 113. The spinner assembly 133 assists in sweeping particles out of the discharge opening. Clean air exits the housing 113 through the outlet passage 119.
In designing an inertial air cleaner, it is desirable to provide a device having a high particulate removal efficiency and a relatively low pressure drop.
One aspect of the present invention relates to an air cleaner for removing particles from an air stream. The air cleaner includes a housing defining a separation chamber at which at least some of the particles are removed from the air stream. The housing includes an inlet passage for allowing the air stream to enter the separation chamber, and an outlet passage for allowing the air stream to exit the separation chamber. The outlet passage includes an air entrance end positioned opposite from an air exit end. The air entrance end of the outlet passage is positioned to receive the air stream from the separation chamber. Adjacent its air entrance end, the outlet passage has a cross-sectional passage area A1. The inlet passage also includes an air entrance end positioned opposite from an air exit end. The air exit end of the inlet passage has a cross-sectional passage area A2. The cross-sectional passage areas A1 and A2 are relatively sized such that A1/A2 is in the range of 0.7-1.9. The air cleaner further includes a plurality of vanes for causing the air stream to swirl as the air stream flows through the inlet passage and enters the separation chamber. A spinner assembly is positioned within the separation chamber for transferring rotational energy from a mid-region of the separation chamber to an outer region of the separation chamber.
Another aspect of the present invention relates to an air cleaner including a housing defining a separation chamber at which at least some of the particles are removed from the air stream. The air cleaner also includes an inlet passage for allowing the air stream to enter the separation chamber, and an outlet tube defining an outlet passage for allowing the air stream to exit the separation chamber. The outlet tube includes: (a) an air entrance end positioned opposite from an air exit end; and (b) a tapered portion positioned adjacent the air entrance end of the outlet tube. The tapered portion of the outlet tube tapers radially outward such that a cross-sectional passage area of the outlet tube increases as the outlet tube extends in a direction toward the air entrance end of the outlet tube. The tapered portion is aligned along an angle xcex8 in the range of 15-45 degrees relative to a central axis of the outlet tube. The inlet passage of the air cleaner is at least partially defined by an outer surface of the outlet tube. The inlet passage includes: (a) an air entrance end positioned opposite from an air exit end; and (b) a transition region provided by the tapered portion of the outlet tube that reduces a cross-sectional passage area of the inlet passage as the inlet passage extends toward the air exit end of the inlet passage. The air cleaner further includes a plurality of vanes for causing the air stream to swirl as the air stream flows through the inlet passage and enters the separation chamber. A spinner assembly is positioned within the separation chamber for transferring rotational energy from a mid-region of the separation chamber to an outer region of the separation chamber.
Still another aspect of the present invention relates to an air cleaner for removing particles from an air stream. The air cleaner includes a housing defining a separation chamber at which at least some of the particles are removed from the air stream. The housing includes a side wall structure surrounding a central axis of the housing. The air cleaner also includes an annular inlet passage for allowing the air stream to enter the separation chamber, an outlet passage for allowing the air stream to exit the separation chamber, and a plurality of vanes for causing the air stream to swirl as the air stream flows through the inlet passage and enters the separation chamber. The annular inlet passage is defined by inner and outer walls. The inner wall includes a transition region that reduces a cross-sectional passage area of the inlet passage as the inlet passage extends toward an air exit end of the inlet passage. The transition region is configured such that no portion of the transition region is aligned at an angle outside a range of 15-45 degrees relative to a central axis of the housing. A spinner assembly is positioned within the separation chamber for transferring rotational energy from a mid-region of the separation chamber to an outer region of the separation chamber.
A variety of advantages of the invention will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practicing the invention. It is to be understood that both the foregoing general description and the following detailed description are illustrative and explanatory only and are not restrictive of the invention as claimed.